scope:

The aim of this document is to provide guidance on how to protect the distributed infrastructure (power, telecommunications, transportation and pipeline networks, etc.) from the threat of a high altitude electromagnetic pulse (HEMP). In order to accomplish this goal, it is necessary to describe the special aspects of the HEMP threat to electrical/electronic systems that are connected and distributed in nature. In particular a nuclear burst at a typical altitude of 100 km will illuminate the Earth to a ground radius from the point directly under the burst to a range of 1 100 km. This means that any distributed and connected infrastructure such as power or telecommunications will observe disturbances simultaneously over a wide area. This type of situation is not normally considered in the EMC or HEMP protection of facilities that are part of a distributed network as the impact of a local disturbance is usually evaluated only locally. This publication provides general information concerning the disturbance levels and protection methods for all types of distributed infrastructures. Due to its importance to all other parts of the infrastructure, the distributed electric power system (power substations, generation plants and control centres) and its protection are described in more detail. While the telecommunication system is also critical to most of the other distributed infrastructures, the protection of the telecommunication network from HEMP and other electromagnetic threats is covered by the work done by ITU-T.